Catalyst for reduced nitrogen oxide (NOx) emissions in an oxodehydrogenation process

Abstract

The present invention discloses a process to treat a ferrite based catalyst useful in the oxidative dehydrogenation of monololefins and diolefins which process includes a preheat step prior to use of the catalyst in the OXO-D reactor. The catalyst is preferably a zinc ferrite catalyst for the production of butadiene. It has been observed that substantially no nitrogen oxide emissions result from the use of this treated catalyst in the reactor unit during the oxidative dehydrogenation reaction.

What is claimed is: 
     
       1. A process for producing a ferrite catalyst suitable for use in an oxydehydrogenation process, comprising preparing a calcined ferrite catalyst formulated with nitrate, and then pre-treating the calcined ferrite catalyst formulated with nitrate with a heat pre-treatment prior to use in an oxydehydrogenation process, wherein the calcined ferrite catalyst formulated with nitrate is heat-treated at a temperature range of about 300° C. to about 650° C., for a time range of about 5 minutes to about 360 minutes (6 hr), in at least one of a fixed bed, rotary kiln, or fluidized bed reactor, under a suitable atmosphere, wherein the heat pre-treated calcined ferrite catalyst formulated with nitrate has a reduced level of surface nitrate groups as compared with the calcined ferrite catalyst formulated with nitrate prior to the heat pre-treatment. 
     
     
       2. The process of  claim 1 , wherein the temperature range of the heat pre-treatment is from about 400 to about 600° C. 
     
     
       3. The process of  claim 2 , wherein the temperature range of the heat pre-treatment is about 450-550° C. 
     
     
       4. The process of  claim 1  including carrying out the heat pre-treatment for a time period of about 5 to about 60 min. 
     
     
       5. The process of  claim 1 , wherein analytical testing is conducted on the resulting heat pre-treated calcined ferrite catalyst formulated with nitrate and comprises IR spectrometry and the characteristic nitrate peak at 1350 cm −1  is monitored. 
     
     
       6. The process of  claim 1  wherein, analytical testing is conducted on the resulting heat pre-treated calcined ferrite catalyst formulated with nitrate modified catalyst and comprises mass spectrometry and oxides of nitrogen are monitored. 
     
     
       7. The process of  claim 1 , wherein the heat pre-treatment of the calcined ferrite catalyst formulated with nitrate is carried out with a fixed bed provided with nitrogen flow, at a temperature of about 500° C., for a time period of about 120 min after reaching 500° C. in the fixed bed reactor. 
     
     
       8. The process of  claim 1 , wherein the heat pre-treatment of the calcined ferrite catalyst formulated with nitrate is carried out in a rotary kiln furnace under air flow, at a temperature of about 500° C., for a time period of about 15 min, after reaching 500° C. in the furnace. 
     
     
       9. The process of  claim 1 , wherein the heat pre-treatment of the calcined ferrite catalyst formulated with nitrate is effective to remove about 75%-98% by weight of the surface nitrate groups. 
     
     
       10. The process of  claim 8 , wherein the heat pre-treatment of the calcined ferrite catalyst formulated with nitrate is effective to remove about 85%-95% by weight of the surface nitrate groups. 
     
     
       11. The process of  claim 1 , wherein heat pre-treatment of the calcined ferrite catalyst formulated with nitrate is carried out under an atmosphere selected from inert gas, air, nitrogen, methane, natural gas, steam and suitable mixtures thereof. 
     
     
       12. The process of  claim 1 , wherein heat pre-treatment of the calcined ferrite catalyst formulated with nitrate is carried out in air. 
     
     
       13. The process of  claim 1 , wherein the heat pre-treated calcined ferrite catalyst formulated with nitrate is substantially free of detectable surface nitrate groups.